Dual-detector electronic monitoring of electron beam selective melting

Electron Beam Selective Melting (EBSM) is an advanced additive manufacturing technique used in many vital industrial fields. However, the lack of process monitoring and quality control is largely restricting the industrial application. The optical-based monitoring methods are hindered by the complex working conditions, such as intensive radiation, elevated temperature, and severe evaporation. Electronic imaging is an alternative monitoring technique which has been introduced into EBSM process. However, the correlation between the electronic signal and topographic features has not been identified. In this study, a dual-detector electronic imaging system was presented for in-situ monitoring of EBSM process. The preliminary experiment shows a linear correlation between the electronic current and surface height gradient, suggesting a sensitive response of the electronic imaging system to surface height variation. In-situ experiment indicates that the electronic imaging system is capable of visualizing the deposited surfaces with plentiful contrasts. Signal fusion between the dual detectors was able to separate the mixed contrasts for identifying various defects, such as pores and fluctuations. The correlation between signal and topography indicates a good potential for in-situ surface reconstruction and in-process quality control during EBSM process.